Hamish,
This is with OpenShift Online (openshift.redhat.com)?
I just tested Online and was able to create an EAP6 application. Are you seeing this error consistently? If so could you provide your account name so I can have our Ops team take a look?
Thanks -Bill

Hi Bill, Mike,
Unable to complete the requested operation due to: Node execution failure (invalid exit code from node). If the problem persists please contact Red Hat support.. Reference ID: 1e91376046234e2db60fc0e727f3215f
That was at about 7am Saturday, May 25, 2013 (NZST) and is the most recent attempt.
If there has been a successful add "My Applications" tab doesn't get me to it, just dumps me back into "Create Application."
Thanks for the efforts.
Hamish.